1. Field of the Invention
The present invention relates to an electrode for an electron gun and to an electron gun using the same.
2. Description of the Related Art
Recently, a carbonaceous material, such as carbon nanotubes which have a work function of a low value and are very stable, has been attracting increasing attention as an electrode material for an electron gun or a cold cathode type electron emission element (FED: Field Emitter Device), as is described, for example, in Japanese Patent Publication No.10-199398.
In order to form an electrode by fixing carbon nanotubes on a substrate of glass, Si, a metal plate, or the like, a method has been conventionally known in which carbon nanotubes are mixed into silver paste or the like and the mixture is applied in liquid form to the substrate by means of screen printing method. An alternative method, as described in the above-mentioned patent publication, is also known in which a layer of carbon nanotubes is directly formed on the substrate by means of a CVD (Chemical Vapor Deposition) method.
A method is also disclosed, although carbon nanotubes are not used, in Japanese Patent Publication No. 2002-100278, in which a carbon plate having graphite crystal grown homogeneously and highly controlled in one direction in amorphous carbon is bonded via an adhesive layer to a substrate to form an emitter.
In the above-mentioned method of using screen printing in liquid form, it is difficult to orientate the carbon nanotubes in one direction. This method has a further disadvantage that blending ratio of carbon nanotube cannot be increased because an increase in viscosity, with an increasing proportion of carbon nanotubes, prohibits screen printing being carried out. The method using CVD to form a layer of carbon nanotubes directly on a substrate has a disadvantage that it takes too many steps and too much time to be carried out at a reasonable cost.
The same problem arises with a hot cathode type electron gun such as a cathode ray tube (CRT) as with above-mentioned cold cathode type electron gun.